From: Segher Boessenkool <segher@kernel.crashing.org>
To: Borislav Petkov <bp@alien8.de>
Cc: "Arvind Sankar" <nivedita@alum.mit.edu>,
"Jakub Jelinek" <jakub@redhat.com>,
jgross@suse.com, x86@kernel.org,
"Kees Cook" <keescook@chromium.org>,
"Peter Zijlstra" <peterz@infradead.org>,
linuxppc-dev@lists.ozlabs.org, "Michael Matz" <matz@suse.de>,
"Nick Desaulniers" <ndesaulniers@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"Sergei Trofimovich" <slyfox@gentoo.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Paul Mackerras" <paulus@samba.org>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Frédéric Pierret (fepitre)" <frederic.pierret@qubes-os.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Martin Liška" <mliska@suse.cz>,
boris.ostrovsky@oracle.com
Subject: Re: [PATCH] x86: Fix early boot crash on gcc-10, next try
Date: Sat, 25 Apr 2020 13:37:01 -0500 [thread overview]
Message-ID: <20200425183701.GE17645@gate.crashing.org> (raw)
In-Reply-To: <20200425173140.GB24294@zn.tnic>
On Sat, Apr 25, 2020 at 07:31:40PM +0200, Borislav Petkov wrote:
> > There's also the one in init/main.c which is used by multiple
> > architectures. On x86 at least, the call to arch_call_rest_init at the
> > end of start_kernel does not get tail-call optimized by gcc-10, but I
> > don't see anything that actually prevents that from happening. We should
> > add the asm("") there as well I think, unless the compiler guys see
> > something about this function that will always prevent the optimization?
>
> Hmm, that's what I was afraid of - having to sprinkle this around. Yah, let's
> wait for compiler guys to have a look here and then maybe I'll convert that
> thing to a macro called
>
> compiler_prevent_tail_call_opt()
>
> or so, so that it can be sprinkled around. ;-\
That is a lot more typing then
asm("");
but more seriously, you probably should explain why you do not want a
tail call *anyway*, and in such a comment you can say that is what the
asm is for.
I don't see anything that prevents the tailcall in current code either,
fwiw.
Segher
next prev parent reply other threads:[~2020-04-25 18:38 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-14 16:44 [PATCH] x86: fix early boot crash on gcc-10 Sergei Trofimovich
2020-03-16 13:04 ` Peter Zijlstra
2020-03-16 13:26 ` Jakub Jelinek
2020-03-16 13:42 ` Peter Zijlstra
2020-03-16 17:54 ` Borislav Petkov
2020-03-16 18:03 ` Jakub Jelinek
2020-03-17 14:36 ` Borislav Petkov
2020-03-17 14:39 ` Jakub Jelinek
2020-03-17 14:49 ` Borislav Petkov
2020-03-17 16:35 ` David Laight
2020-03-25 13:31 ` Borislav Petkov
2020-03-26 21:54 ` Sergei Trofimovich
2020-03-26 22:35 ` Borislav Petkov
2020-03-28 8:48 ` [PATCH v2] " Sergei Trofimovich
2020-04-13 14:15 ` [tip: x86/urgent] x86: Fix " tip-bot2 for Sergei Trofimovich
2020-04-13 16:35 ` [PATCH v2] x86: fix " Borislav Petkov
2020-04-14 13:50 ` Michael Matz
2020-04-15 7:48 ` Borislav Petkov
2020-04-15 14:53 ` Michael Matz
2020-04-15 22:19 ` Sergei Trofimovich
2020-04-17 7:57 ` Borislav Petkov
2020-04-17 8:07 ` Jakub Jelinek
2020-04-17 8:42 ` Borislav Petkov
2020-04-17 8:58 ` Jakub Jelinek
2020-04-17 9:09 ` Borislav Petkov
2020-04-17 18:15 ` Nick Desaulniers
2020-04-17 18:22 ` Nick Desaulniers
2020-04-17 19:06 ` Jakub Jelinek
2020-04-17 19:49 ` Nick Desaulniers
2020-04-17 19:53 ` Nick Desaulniers
2020-04-20 14:04 ` Michael Matz
2020-04-22 10:23 ` Borislav Petkov
2020-04-22 11:40 ` Peter Zijlstra
2020-04-22 13:49 ` Borislav Petkov
2020-04-22 13:55 ` Jakub Jelinek
2020-04-22 14:16 ` Martin Liška
2020-04-22 15:06 ` Michael Matz
2020-04-22 16:53 ` Borislav Petkov
2020-04-22 17:02 ` Jakub Jelinek
2020-04-22 18:47 ` Nick Desaulniers
2020-04-22 18:55 ` Nick Desaulniers
2020-04-22 19:21 ` Borislav Petkov
2020-04-22 21:05 ` Nick Desaulniers
2020-04-22 21:26 ` Borislav Petkov
2020-04-22 22:57 ` Nick Desaulniers
2020-04-23 12:53 ` Borislav Petkov
2020-04-23 16:12 ` [PATCH] x86: Fix early boot crash on gcc-10, next try Borislav Petkov
2020-04-23 17:30 ` Borislav Petkov
2020-04-23 18:02 ` Nick Desaulniers
2020-04-23 18:27 ` Borislav Petkov
2020-04-27 11:37 ` [tip: x86/build] x86/build: Check whether the compiler is sane tip-bot2 for Borislav Petkov
2020-04-23 19:40 ` [PATCH] x86: Fix early boot crash on gcc-10, next try Kees Cook
2020-04-25 1:46 ` Arvind Sankar
2020-04-25 8:57 ` Borislav Petkov
2020-04-25 11:09 ` Jürgen Groß
2020-04-25 15:04 ` Arvind Sankar
2020-04-25 17:31 ` Borislav Petkov
2020-04-25 17:52 ` Borislav Petkov
2020-04-27 17:07 ` David Laight
2020-04-25 18:37 ` Segher Boessenkool [this message]
2020-04-25 18:53 ` Borislav Petkov
2020-04-25 19:15 ` Segher Boessenkool
2020-04-25 22:17 ` Borislav Petkov
2020-04-25 22:25 ` Arvind Sankar
2020-04-17 10:38 ` [PATCH v2] x86: fix early boot crash on gcc-10 Peter Zijlstra
2020-04-18 13:12 ` David Laight
2020-04-17 10:41 ` Peter Zijlstra
2020-03-16 18:20 ` [PATCH] " Arvind Sankar
2020-03-16 18:54 ` Arvind Sankar
2020-03-16 19:53 ` Arvind Sankar
2020-03-16 20:08 ` Jakub Jelinek
2020-03-16 20:40 ` Arvind Sankar
2020-03-16 22:12 ` Sergei Trofimovich
2020-03-17 11:46 ` Jakub Jelinek
2020-03-17 18:10 ` Sergei Trofimovich
2020-03-16 18:22 ` Arvind Sankar
2020-03-26 23:16 ` [PATCH v2] " Sergei Trofimovich
2020-04-27 11:37 ` [tip: x86/build] x86: Fix early boot crash on gcc-10, next try tip-bot2 for Borislav Petkov
2020-05-15 11:20 ` [tip: x86/urgent] x86: Fix early boot crash on gcc-10, third try tip-bot2 for Borislav Petkov
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